Because ESM and AA modules are part of integrated service offering (ESM with residential AA on the same node), they share the same subscriber-id string. However, Gx interface in ESM is primarily applicable to hosts (basic entity to which policy is applied) while AA has no awareness of hosts. AA is only aware of subscribers (which is, in broader terms, a collection of hosts within a residence). See the 7450 ESS, 7750 SR, and VSR Multiservice ISA and ESA Guide for details on Application Assurance concepts.